Black light serves security
For security applications where light must see without been seen, Osram has introduced the Oslon black led.
The FH 4725S, available from Rutronik, has a wavelength of 940nm (rather than the more normal 850nm), making it almost invisible to the human eye. It is also housed in a black package which reflects no ambient light.
While camera sensors can easily pick up the 940nm wavelength, the human eye is 130 times less likely to notice it.
The infrared led is compact, measuring 3.85x3.85x2.29mm, and provides an optical output of 980 milliwatts from an operating current of 1A. Behind this performance lies the Nanostack technology in which two emission centres are provided in one chip, almost doubling the light output. The SFH 4725S achieves a radiant intensity of 450mW/sr at an emission angle of 90°.
